There have been many attempts in recent years to produce a commercially acceptable synthetic suede-like product. Such materials have been sought primarily for the manufacture of various garments such as dresses, suits, rainwear, and the like. Natural suede has been used for such purposes, but it is a relatively expensive material and often represents the major portion of the costs of making the garments. Moreover, natural suede has the disadvantage of readily showing dirt or other spots on its surface and therefore requires constant cleaning and brushing to maintain its attractive appearance. Natural suede is also easily stained, and such stains are difficult if not impossible to remove without damaging the original appearance and feel.
Some of the process proposed heretofore for the preparation of synthetic suede are described in U.S. Pat. Nos. 2,835,607; 3,098,263; 3,141,051; 3,190,947; 3,316,592; 3,655,497; and 3,705,226. The prior art processes have a number of serious disadvantages; the main problem in most instances being the failure of the synthetic suede product to have properties which are sufficiently similar to natural suede so that the consumer is satisfied. In other instances, the processing procedures are so complicated and involved that the final synthetic product is as expensive, if not more expensive, than natural suede. A number of the prior art processes have the disadvantages of requiring the use of expensive apparatus and/or a large number of processing steps.
U.S. Pat. No. 3,705,226 which pertains to a method for preparing the so-called "Ultrasuede" involves a relatively large number of processing steps, chemical impregnations, and solvent treatments. It would be desirable therefore to have a process available for producing a comparable synthetic suede product which did not require so many processing steps, chemical impregnations, and solvent treatments.
The known synthetic suede products generally are prepared by forming a woven or non-woven substrate from fibrous or textile materials; coating said substrate with a solution, plastisol or film of plastic material; and then fiberizing the resulting adherent coating by such conventional means as sueding, brushing, grinding, napping, shearing, etc.
One object of the present invention is to provide an improved process for the manufacture of synthetic suede which avoids disadvantages of the prior art processes.
Another object of the present invention is to provide a continuous process for the manufacture of synthetic suede by a series of sequential steps that do not include chemical and/or solvent treatments.
A further object of the present invention is to provide an outstanding synthetic suede product having surfaces with outwardly extending, non-tapered fibers and body characteristics having the hand, drape, moderate yield and slow recovery qualities normally associated with genuine leather suede.
A still further object of the present invention is to provide a synthetic suede product prepared from non-fibrous and non-textile feed materials.
These and other objects of the present invention are achieved by the discovery that an improved synthetic suede product can be manufactured in a continuous manner by supplying at least three separate non-fibrous, non-textile feed materials into the nip formed by two rotating, heated cyclinders carrying two endless, flexible molding bands provided with a multiplicity of minute molding cavities. Two of the feed materials are polyurethane films or sheets which form the outer layers of the product and from which outwardly extending fibers are produced by the molding cavities. The other feed material may be a polyurethane film, sheet, web or foam. The latter feed material forms the inner layer of the improved suede product of this invention. The three or more separate feed materials are welded together under elevated temperatures and pressures while being passed through the nip. At the same time, the outer polyurethane components in the feed material are in a molten or semi-molten condition and a portion thereof flow into the cavities of the molding bands to form the outwardly extending fibers or hairs on both outer surfaces, i.e., the stop and bottom surface layers of the composite assembly.